Air pump

ABSTRACT

An air pump is provided that is configured to move and compress air into an air storage vessel at high pressure. The air pump is operable to move large volumes of air against low resistance for rapid filling of an air storage vessel.

FIELD OF THE INVENTION

The invention relates to an air pump and specifically to an air pump for moving and compressing air into an air storage tank.

BACKGROUND OF THE INVENTION

Air pumps are used to transport a volume of air from one location to another. Air pumps that act as compressors are known to move and store a volume of air from one location to an air storage tank. When compressing and storing air considerable mechanical work may be required to store a required volume of air at a required pressure.

In order to store large volumes of air within a short amount of time, a large air pump is generally required in order to be able to move the required volume within the limited time. Smaller air pumps will generally only move a small volume of air and will therefore require more time in which to fill a large air storage tank.

SUMMARY OF THE INVENTION

The present invention provides an air pump comprising an internal by-pass system that allows air to flow directly from each air piston to the air storage tank depending on the pressure of the air moving between the pistons and the pressure head in the air storage tank.

In one embodiment, there is provided an air pump including a series of air pistons that are configured to pass air between adjacent pistons and to an air storage tank using a by-pass system.

In an alternative embodiment, there is provided an air pump configured to allow for movement of air to and from an air storage tank comprising a housing having at least one stem passing therethrough, the stem configured to reciprocate along its longitudinal axis within the housing, at least two air pistons located within respective air piston bores within the housing, each of the air pistons connected to the at least one stem and configured to reciprocate, along the longitudinal axis of the at least one stem, within its respective air piston bore, each air piston bore comprising a first air line fluidly connecting the air piston bore to the air storage tank and at least one second air line fluidly connecting the air piston bore to an adjacent air piston bore.

In an alternate embodiment, the air pump described herein further comprises an actuator for moving the at least one stem along its longitudinal axis within the housing. In one embodiment, the actuator is a hydraulic pump.

In an alternate embodiment, the first air line is configured to allow passage of air from the air piston bore to the air storage tank when the air leaving the air piston bore is of equal or greater pressure than the air in the air storage tank.

In a further embodiment, an air pump is provided that is configured to allow for movement of air to and from an air storage tank comprising a housing having a first and second stem passing therethrough, each of the stems configured to reciprocate along their longitudinal axis within the housing. The air pump further comprises a first air piston connected to the first stem and received within a first air piston bore located within the housing, the first air piston being operable to reciprocate within the first air piston bore along the longitudinal axis of the first stem; a second air piston connected to the first stem and received within a second air piston bore located within the housing, the second air piston being operable to reciprocate within the second air piston bore along the longitudinal axis of the first stem; a first air line, fluidly connecting the first piston bore to the air storage tank; a second air line, fluidly connecting the first piston bore to the second piston bore; and a third air line fluidly connecting the second piston bore to the air storage tank. The air pump further includes a third air piston connected to the second stem and received within a third air piston bore located within the housing, the third air piston being operable to reciprocate within the third air piston bore along the longitudinal axis of the second stem; a fourth air piston connected to the second stem and received within a second air piston bore located within the housing, the fourth air piston being operable to reciprocate within the second air piston bore along the longitudinal axis of the second stem; a fourth air line, fluidly connecting the third piston bore to the air storage tank; a fifth air line, fluidly connecting the third piston bore to the fourth piston bore; and a sixth air line fluidly connecting the fourth piston bore to the air storage tank.

In another embodiment, the air pump described above includes at least one actuator, for moving at least one of the first and second stem along its respective longitudinal axis within the housing. In an alternative embodiment, the air pump includes a first and a second actuator, the first actuator for moving the first stem along its respective longitudinal axis within the housing and the second actuator for moving the second stem along its respective longitudinal axis within the housing.

In an alternate embodiment, a method is provided for moving and compressing air using an air pump comprising a series of air pistons fluidly connected to each other and to an air storage tank, the method comprising (a) moving air between adjacent air pistons within the air pump and (b) allowing air to flow from each air piston to the air storage tank when the air pressure of the air leaving the air piston is equal to or exceeds the pressure in the air storage tank.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in further detail with reference to the following figures:

FIG. 1 is a schematic of one embodiment of an air pump described herein;

FIG. 2 is an alternative schematic of the air pump of FIG. 1 including an air storage tank and air lines;

FIGS. 3A and 3B show one embodiment of the air pump in the air pump mode with the by pass mode off;

FIGS. 4A and 4B show another embodiment of the air pump in the air pump mode with the by pass mode on;

FIGS. 5 A-C show an alternative embodiment of the air pump in the motor mode configuration;

FIG. 6 shows an alternate embodiment of the air pump in a double stage, single rod configuration;

FIG. 7 shows an alternate embodiment of the air pump in a double stage split rod configuration; and

FIG. 8 shows one embodiment of the double stage split rod configuration, with the split rods moving in opposing direction;

FIG. 9 shows another embodiment of the double stage split rod configuration, with the split rods moving in an offset configuration; and

FIGS. 10A-B show another embodiment of the double stage split rod configuration in playback mode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides an air pump that moves and compresses air through a series of air pistons into an air storage tank at high pressure. The air pump includes a series of air pistons, connected by a common connecting rod, that simultaneously reciprocate to move air from one piston to the next for eventual storage in an air storage tank.

The air pump includes an internal by-pass system that allows air to flow directly from each air piston to the air storage tank depending on the pressure of the air moving between the pistons and the pressure head in the air storage tank. The by-pass system allows for large volumes of air to be passed directly to the air storage tank against low resistance, i.e. when the pressure in the tank is low, to provide rapid filling of the air storage tank. As the pressure rises in the air storage tank, the by pass system allows the air to pass between adjacent air pistons until the pressure of the air forced out of an air piston bore by an air piston is equal to or greater than the air pressure in the air storage tank. When this occurs the air will flow directly to the air storage tank. The by pass system allows the air pump, and particularly the air pistons to move the air efficiently for rapid filling of the air storage tank.

It will be understood that the use of the term “by-pass system” refers to the passage/flow of the air through the air lines that connect the air pistons within the air pump and that connect the air pump to the air storage tank, as described further below.

The air pump described herein may be configured to work as an air pump or a motor device. The air pump may include different configurations of pistons and connecting rods, e.g. single rod or split connecting rods, depending on the specific use of the air pump.

The air pump includes a series of pistons having decreased diameters which allows for staged compression of the air between adjacent pistons. The larger pistons are able to move larger volumes of air relative to the smaller pistons, however the air that is pumped out of the larger pistons is of a lower pressure than the air that is pumped out of the smaller pistons. The air pump, and in particular the by-pass system, allows for a larger volume of air to be pumped directly from the larger air piston to the air storage tank when the air pressure inside the air storage tank is at a low pressure. As the air pressure in the air storage tank increases the air is no longer able to flow directly from the larger piston and instead it flows to the adjacent smaller piston which is operable to pump air out at a higher pressure which is then able to flow to the air storage tank. As the air pressure increases in the air storage tank, only the air pumped from the smallest air piston is able to reach the same pressure as the air in the air storage tank and is therefore able to flow to the air storage tank. Once the air in the air storage tank reaches the maximum pressure setting, any excess air will blow-off via a pressure relief valve.

The present invention will now be described in detail with reference to the accompanying Figures.

One embodiment of a single stage air pump is shown in FIG. 1 in which the air pump is indicated generally at numeral 10. The air pump 10 includes a housing 12 that is configured to house a hydraulic piston 14 and a series of air pistons 16, 18, 20, which are all connected to rod 22.

Each of the air pistons 16, 18 and 20 and the hydraulic piston 14 are connected to the rod 22 so as to move simultaneously with the rod 22 and adjacent pistons.

Each piston 14, 16, 18 and 20 is received within a corresponding piston bore 24, 26, 28, 30 located within the housing 12. Each bore 24, 26, 28, 30 is sized to receive the corresponding piston 14, 16, 18, 20 and to allow for reciprocation of the piston 14, 16, 18, 20 within the bore 24, 26, 28, 30.

As can be seen in FIG. 1, the hydraulic piston 14 is received within the piston bore 24 which is fluidly connected to a source of hydraulic fluid through hydraulic fluid inlets 32, 34 and hydraulic fluid outlets 36, 38. In an alternative embodiment, not shown, the piston bore 24 may include only two ports, each including a crossover valve to allow for fluid to flow in or out of the respective port to which it is connected. The direction of fluid flow will be chosen based on the use of the air pump.

It will be understood that the source of the hydraulic fluid may be any source that is operable to supply fluid at the required pressure to move the hydraulic piston 14 for use in the air pump 10. The operation and use of the air pump 10 will be described in further detail below. The hydraulic fluid enters the piston bore 24 through one of the hydraulic fluid inlets 32, 34, depending on the position of the hydraulic piston 14, and the pressure and amount of fluid initiates movement of the hydraulic piston 14 within the hydraulic piston bore 24.

As can be seen in FIG. 1, sequential air pistons 16, 18, 20 have smaller diameters as you move along the rod 22 from air piston 16 to air piston 20. Each of the air piston bores 26, 28, 30 are sized to receive the respective air piston 16, 18, 20 to allow for reciprocating movement of the piston within its respective bore.

Each of the piston bores include respective air inlets and air outlets, referred to herein as air ports, shown clearly in FIG. 2. Each of the air ports allow air to enter and/or exit the piston bore and allows the air to pass into or out of the respective air line to which the port is connected. The use of the air lines and air ports will be described in more detail below in the description of the operation of the air pump 10.

Each piston bore is divided, by the position of the piston within the piston bore, into two parts which are referred to herein as A and B. For example, in FIG. 2, piston bore 26 includes part A, located on the left side of the piston 16 when viewing FIG. 2, and part B, located on the right side of piston 16 when viewing FIG. 2. For ease of reference when describing the operation of the air pump 10, each part will be referred to herein as piston bore 26A or piston bore 26B but it will be understood that each part A and B form the complete piston bore 26 and vary in size during operation of the air pump due to the movement of each piston within each piston bore. It will be understood that adjacent piston bores 26, 28, 30 are separated via a fixed dividing wall.

Each of the respective air piston bores 26, 28, 30 are fluidly connected to the adjacent piston bore(s), and further are configured to be fluidly connected to an air storage tank 100, shown in FIG. 2, both directly, shown in FIGS. 4A and 4B, or indirectly through air flow through respective piston bores 26, 28, 30. As will be understood by the description provided below, each of the air pistons 16, 18, 20 are operable to drive air from their respective piston bore 26, 28, 30 to the adjacent piston bore, or directly to the air storage tank 100, depending on the pressure of the air leaving the piston bore and the head pressure of the storage tank 100. The piston bores 26, 28, 30 are fluidly connected to the storage tank 100 through a series of air lines, that will be described in further detail below. It will be understood that the discussion of the air lines will refer to the schematic figures provided, where air lines will be referred to using numerical references. While only one numeral may be referred to in the description it will be understood that each air line may consist of several different air lines all interconnected. A person skilled in the art will understand that different configurations for the air lines may be used provided that the air is able to flow as described herein. The air pump is not limited to the air lines shown in the Figures, which are included as examples with respect to the general discussion of air flow. It will be understood that some of the air lines shown may be combined and arranged to include valves that allow for the flow of air through an adjacent air line or out to ambient, depending on the use of the air pump. It will be understood that the air flow between adjacent air piston bores and/or the air storage tank may flow along different air lines provided that it passes between respective piston bores and the air storage tank as described.

The configuration of the piston bores 26, 28, 30 being fluidly connected directly to the air storage tank 100 is referred to herein as the “by pass” system. It will be understood that the air pump 10 described herein can be operated with the by pass system turned on or off. The by pass system will work, i.e. air will flow through the air lines to the air storage tank 100, when there is no or low air pressure in the air storage tank 100. The by pass system allows air to flow to the tank when there is low or no pressure in the tank, which means that larger volumes of air are not handed off to the adjacent smaller piston. This eliminates the need to pass the air through adjacent pistons, and through further compression stages, and allows for more rapid filling of the air storage tank. This will be described in further detail below.

As stated above, each consecutive air piston 16, 28, 20 has a smaller diameter as you move from air piston 16 to air piston 20. Likewise the respective piston bores 26, 28, 30 are of decreasing overall volume. As a result of the decreasing size of the piston bores 26, 28, 30, each piston bore is able to hold a different volume of air and consequently the air leaving consecutive piston bores is forced out of the piston bores at consecutively higher pressures. It will be understood that all of the piston bores have the same depth in order for them to all accommodate the same stroke length.

FIG. 2 shows one embodiment of the air pump 10 with the air ports and air lines showing one embodiment of the connection of the piston bores 16, 18, 20 to each other and to the air storage tank 100. While the operation of the air pump 10 will not be described with reference to FIG. 2, this Figures shows one embodiment of the various connections as follows.

For ease of reference, the hydraulic piston 14 is shown in the middle of a stroke in the centre of hydraulic piston bore 24. Fluid is operable to flow into the hydraulic piston bore 24 through one of the inlets 32, 34 and out through one of the outlets 36, 38.

Each of the air pistons 16, 18, 20 are shown in the centre of their respective piston bores 26, 28, 30 with parts A and B indicated within the piston bores. Each of the piston bores 26, 28, 30 are fluidly coupled to air ports that allow the air to flow into and out of the piston bores 26, 28, 30. It will be understood that each piston bore 26, 28, 30 includes four air ports connected to four air lines the air ports are shown in FIG. 1. Piston bore 26 includes air ports 40, 42, 44, 46, piston bore 28 includes air ports 50, 52, 54, 56 and piston bore 30 includes air ports 60, 62, 64, 66. Each air port is connected to an air line that allows the air to flow through the air port through the air line to an adjacent piston bore and/or to the air storage tank. The examples provided below provide various embodiments of the operation of the air pump, and the configuration of the air lines used therein. However, it will be understood that the configuration of the air lines connecting the piston bores and the air storage tank are not limited to the embodiments shown herein and may use other configurations while allowing air to flow between respective piston bores and/or the air storage tank, as described herein.

By Pass System

As stated above, each of the piston bores 26, 28, 30 are connected to adjacent bores through a series of air lines and air ports. In addition, each of the piston bores 26, 28, 30 are also fluidly connected to the air storage tank 100 via a series of air lines. Each of the air lines includes at least one check valve which prevents air from flowing back along the air line. When the by pass system is “on”, the direction of the flow of the air through the air lines will be governed by the pressure of the air leaving the piston bore(s) and the head pressure in the air storage tank 100. When the head pressure in the air storage tank 100 is low, or when there is no air in the tank, the air that is forced out of piston bore 26 is able to flow directly to the air storage tank 100 since there is little or no resistance to its flow. The air storage tank 100 then begins to fill up with the air thereby increasing the head pressure within the storage tank 100. Since the volume of air that flows from the piston bore 26 is larger than the volume of air that flows from piston bore 30, it will be understood that air that flows directly from piston bore 26 will fill the air storage tank 100 at a greater rate than air that flows only from piston bore 30 to the air storage tank 100. This allows for large volumes of air to be moved directly into the air storage tank 100 from piston bore 26 providing rapid filling of the air storage tank 100.

Initially, when the pressure in the storage tank 100 is low the air leaving piston bore 26 will be able to flow directly to the storage tank 100. However, as the head pressure in the storage tank 100 increases, the air leaving piston bore 26 will be at too low a pressure to be able to flow directly to the air storage tank 100 and will instead flow directly to piston bore 28. The air leaving piston bore 28, which will be at a higher pressure then that leaving piston bore 26, may be able to flow directly to the air storage tank 100 due to its higher pressure. Therefore, air will continue to by-pass to the air storage tank 100 filling it up. Eventually, the pressure within air storage tank 100 will be high, due to the fact that the storage tank 100 has been filled with air flowing through the by pass system from the air pump 10. At this point, only air that leaves piston bore 30 will be at a pressure that allows the air to flow directly to the air storage tank 100.

It will be understood that the ability of the air pump 10 to pump air directly to the air storage tank 100 from the first piston bore 26 provides an air pump that moves and compresses air into the storage tank 100 at a greater rate than a traditional pump. The air pump 10 has the ability to move larger volumes of air, using the by pass system, against low resistance, in order to rapidly fill the air storage tank 100, when required.

As will be understood by the descriptions provided below, several configurations of the air pump 10 are described herein. However, it will be understood that the use of the air pump 10 is not limited to the examples provided and other configurations may be used.

The operation of the air pump will now be described in various configurations including the air pump mode with the by-pass system “off”, the air pump mode with the by-pass system “on” and the motor mode. It will be understood that reference is made generally to air lines that connect adjacent piston bores and/or the air storage tank and the piston bores, however the air lines described below, and identified in the figures are not meant to be limiting in any way. The air pump may comprise any series or combination of air lines that fluidly connect the piston bores and air storage tank as described herein. Reference to the specific air lines identified in the figures is provided to assist in the general understanding of the operation of the air pump. In the figures, the dashed lines indicate air lines that are dormant and the solid lines indicate air lines that are live. Solenoid valves are indicated generally by the symbol

, showing a closed solenoid valve, and

showing an open solenoid valve. For ease of reference, solenoid valves are not specifically identified by numeral, however their use within the air lines will be understood clearly by a person skilled in the art and are discussed specifically where applicable.

With respect to the following discussions of the various configurations and modes of operation of the air pump, the fluid inlets and outlets and air ports which are referred to are clearly shown in FIG. 1. The actual inlets and outlets and air ports are not specifically identified in FIGS. 3-5, however, a person skilled in the art will understand that they are located at the end of the air lines and fluidly connect the piston bores to the air lines. The inlets/outlets and air ports are clearly identified in FIG. 1. The exact location of the air inlets/outlets and ports is not limited to those positions shown, however they should be positioned, with respective to the piston bores and air lines, to allow for the flow and passage of air as described herein.

Air Pump Single Stage Bypass Off

The operation of the air pump 10, in the air pump single stage with the by-pass system “off” configuration, will now be described with reference to FIGS. 3A and 3B. These figures show the air pump 10 with the bypass mode “off”. FIG. 3A shows the air pump 10 in the bypass “off” mode at the beginning of a stroke that moves from right to left in the direction of arrow “L”. Hydraulic fluid enters the hydraulic piston bore 24 through fluid inlet 32, not shown, at a predetermined pressure. As the hydraulic fluid enters the hydraulic piston bore 24, on the right side of the hydraulic piston 14, the hydraulic piston 14 moves within hydraulic piston bore 24 in the direction of Arrow “L”, shown in FIG. 3A.

Movement of the hydraulic piston 14, which is connected to rod 22, initiates movement of the air pistons 16, 18, 20 which are also connected to rod 22. As air piston 16 begins to move within air piston bore 26 the air port 44, shown in FIG. 1, opens and allows ambient air to flow into air piston bore 26B. As the air piston 16 moves within air piston bore 26 air that is located in piston bore 26A is pushed out of air port 42, shown in FIG. 1, along an air line, indicated generally at 70, into air piston bore 28A through air port 50,

As stated above, movement of rod 22 translates into movement of all the adjacent air pistons 16, 18, 20. Therefore, when rod 22 moves, air piston 18 also moves within air piston bore 28 pushing the air that is located in air piston bore 28B out of air port 56, shown in FIG. 1, through air line 72 into air piston bore 30B through air port 64. The simultaneous movement of air piston 20 within air piston bore 30 pushes the air located in air piston bore 30A out of the air port 62, shown in FIG. 1, into an air line 74 that feeds directly into the air storage tank 100. As the air pump 10 reaches the end of its first stroke when air piston 20 reaches the end of air piston bore 30, all of the air previously located in air piston bore 30A has been expelled and has passed through to air storage tank 100.

On the return stoke, shown in FIG. 3B, hydraulic fluid enters the hydraulic fluid bore 24 through fluid inlet 34, shown in FIG. 1, and the hydraulic piston 14 moves in the direction of the arrow indicated at “R”. As the hydraulic piston 14 and the rod 22 move in the direction of arrow “R”, the air pistons 16, 18, 20 connected to the rod 22 also move. As air piston 16 moves, the air located in air piston bore 26B is pushed out of the bore through air port 40, shown in FIG. 1, along air line 76 and through air port 52, shown in FIG. 1, into air piston bore 28B. Likewise, air located in air piston bore 28A will be pushed out, through movement of air piston 18 within the bore 28, through air port 54, shown in FIG. 1, along air line 78 and through air port 66, shown in FIG. 1, into air piston bore 30A. Finally, air located in air piston bore 30B will be pushed out of air port 64,shown in FIG. 1, through the movement of air piston 20 within air piston bore 30 along air line 80 into air storage tank 100.

Air Pump Single Stage Bypass On

Turning now to FIGS. 4A and 4B, the air pump in the single stage air pump with the by-pass “on” configuration, will now be described with the bypass mode “on”. At the beginning of the stroke, hydraulic fluid enters hydraulic bore 24 through inlet 32, not shown, and the pressure of the hydraulic fluid moves the hydraulic piston 14 within hydraulic piston bore 24 in the direction of Arrow “L”. This in turn moves the air pistons 16, 18, 20 in the direction of Arrow “L” through their connection to rod 22.

As air piston 16 moves within air piston bore 26, air is forced from air piston bore 26A through air port 42, shown in FIG. 1, into air line 70 and simultaneously ambient air is pumped into air bore 26B through air port 44, shown in FIG. 1, from air line 71, to avoid a vacuum in piston bore 26B. As the air is forced out of air piston bore 26A through air port 42, shown in FIG. 1, the air travels along air line 70 and the majority of the air flows directly to air storage tank 100, through air line 82 which is fluidly connected to air line 70, while some air also flows into air piston bore 28A through air port 50, shown in FIG. 1. When the head pressure in air storage tank 100 is low, or there is no air within the storage tank 100, the air leaving air piston bore 26A will be able to flow directly along air line 82 to air storage tank 100 due to the lack of air pressure within the tank 100 which provides a low head pressure against which the air can flow. As air enters the air storage tank 100 the tank will begin to be pre-charged.

If the air pressure in air storage tank 100 is high, and at a pressure that is higher than the pressure of the air leaving air bore 26A, then the air will flow directly through to air piston bore 28A along air line 70 and will not be able to flow along air line 82 due to the greater resistance found in the air storage tank 100. As air piston 18 moves within air piston bore 28, air is forced from air piston bore 28B out of air port 56, shown in FIG. 1, along air line 72, the air that leaves air piston bore 28B may either flow directly into the air storage tank 100, via air line 84 which is fluidly connected to air line 72 or directly into air piston bore 30B through air port 64, shown in FIG. 1.

If the pressure in the air storage tank is lower then the air pressure leaving air piston bore 28B then the air will flow directly to the storage tank 100 as well as through to piston bore 30B. If the pressure in air storage tank 100 is higher than the pressure of the air leaving air piston bore 28B then the air will flow directly into air piston bore 30B.

As air piston 20 moves within air piston bore 30, the air located in air piston bore 30A is pushed out of air port 62, shown in FIG. 1, along air line 74 and directly into the air storage tank 100.

Turning now to FIG. 4B, the return stroke of the single stage air pump mode with the bypass mode “on” will now be described. On the return stroke, as hydraulic fluid is pumped into hydraulic fluid bore 24 through inlet 34, shown in FIG. 1, the hydraulic piston 14 moves within hydraulic piston bore 24 in the direction of Arrow “R”.

As the pistons 16, 18, 20 begin to move in direction “R”, the air located in air piston bore 26B is pushed out of air port 40 by the movement of air piston 16 within air piston bore 26. The air flows out of air port 40 along air line 82 via air line 76 through to the air storage tank 100 and also into air piston bore 28B via air line 76, to prevent a vacuum forming in piston bore 28B. Likewise, the air located in air piston bore 28A flows out of air port 50 directly to the air storage tank 100 along air line 88 and also to piston bore 30A through air port 60, to prevent a vacuum within piston bore 30A. Air that is located in the piston bore 30B is pushed through air port 60 directly to the air storage tank 100, along air line 80, through the movement of air piston 20 within air piston bore 30.

As described above, the air pump 10 can operate as an air pump that moves and stores air, as described above with reference to FIGS. 3A-B and 4A-B. The air pump 10 can also operate as an air motor, also referred to herein as operating in playback mode. In the playback mode the air pump is able to receive the air stored in the air storage tank 100. The air passes back through the air pistons 16, 18, 20 which in turn drives the hydraulic piston 14 thereby activating the hydraulic fluid located in the hydraulic piston bore 24 and pumping it out of the hydraulic piston bore 24.

Air Motor Single Stage (Playback Mode)

The operation of the air pump 10 will now be described in the motor mode or playback mode with reference to FIGS. 5A-D. In this mode the air stored in the air storage tank 100 is used to drive the air pistons 16, 18, 20, and in turn the hydraulic piston 14.

In the playback mode, air is released from the storage tank 100 into piston bore 30A through air port 62, shown in FIG. 1, via air line 90 The air, which is at a high pressure, leaves the storage tank 100 and flows through the air line 90 connecting the storage tank 100 to piston bore 30, and specifically part 30A. It will be understood that a valve, such as a solenoid valve, may be used in the air line to open and close the air line to allow the air to flow through it. Upon opening of the solenoid valve, air flows through the air line into piston bore 30A which drives the pistons 16, 18, 20 in the direction of arrow “R” indicated in FIG. 5A.

As the pistons 16, 18, 20 begin to move, the air in piston bore 30B will flow along air line 89 into piston bore 28B. The air in piston bore 28A flows into piston bore 26A via solenoid valve 110, located between, and in fluid communication with, piston bore 28A and 28B. It will be understood that solenoid valve 110 may alternatively be a separate air line connecting 28A and 28B that includes a solenoid valve within it. In order to avoid a vacuum being created in piston bores 28B air is fed through air line 71 into piston bore 28B.

On the return stroke, indicated by arrow “L” shown in FIG. 5B, the air line 90, through which the air travelled from the air storage tank 100 to piston bore 30A, is now closed, i.e. the valve within the air line 90 is closed.

At the beginning of the stroke air is fed through air line 80 into piston bore 30B. As piston 20 moves within piston bore 30, in the direction of arrow “L”, the air that is in piston bore 30A is forced out and along air line 98 through to air line 88 which allows the air to flow from piston bore 30A to piston bore 28A. As piston 18 moves within piston bore 28, the air that is in piston bore 28B along air line 73 into piston bore 26B. As piston 16 moves within piston bore 26, the air that is in piston bore 26A is forced to ambient through air port 46 and solenoid valve 112.

On the next stroke, shown in FIG. 5C, the air pistons move from left to right in the direction of arrow “R”. A new injection of pressurized air is received in piston bore 30A from air storage tank 100 via air line 90 through air port 62, shown in FIG. 1. This initial injection of air moves air piston 20 in the direction of arrow “R” within piston bore 30. The air in piston bore 30B flows out of air port 60, shown in FIG. 1, along air line 89 into piston bore 28B. Air that is located in piston bore 28A is forced through the movement of air piston 18 from piston bore 28A through solenoid valve 110 into piston bore 26A. Air that is located in piston bore 26B is vented to ambient through air port 44 via solenoid valve 114.

The movement of the air between the air pistons, and thereby the movement of the air pistons, drives the hydraulic piston, which in turn drives hydraulic fluid out of the hydraulic piston bore 24. In this motor mode, the next stroke then moves as that described in FIG. 5A and the cycle of movement repeats. It will be understood from the description of the playback mode that regardless of the volume of air or pressure of the air in the air storage tank, the air is moved through all of the air pistons within the air pump to ensure that all the available energy is used.

It can therefore be seen that in the motor mode, or playback configuration, the air in the air storage tank can be used to drive the air pump, and specifically the air pistons, to in turn drive the hydraulic piston and eject the hydraulic fluid at a high pressure for use in another device or system.

Turning to FIG. 6, an alternative configuration of the air pump is shown. In this configuration, the air pump 610 consists of a double stage air pump with a single rod. In other words, the air pump consists of a series of six air pistons and one hydraulic piston 614 all connected to a single rod 622. The six air pistons are separated into two sets of three air pistons, indicated generally at 611 and 613 located on opposite sides of the hydraulic piston. Each of the two sets of pistons are configured in the same manner, i.e. the air pistons and piston bores are all sized as described above for the single air pump 10. The operation of each of the sets of pistons is also the same as described above in terms of the air flow between respective air piston bores and the air storage tank 100. However, it will be understood that within one stroke the air flow on one side of the air pump 610, for example in air piston set 611 is opposite to that of the air flow in the other air piston set 613.

In another embodiment, shown in FIG. 7, a split rod design is used. As can be seen from FIG. 7, the air pump 710 having the split rod design includes the use of two sets of three air pistons, indicated generally at 711, 713 each connected to separate rods 722, 723. The hydraulic pistons 714, 715 of each of the air piston sets 711, 713 are fed hydraulic fluid from one source which feeds inlets 732, 733. It will be understood that this split rod design is not limited to having one hydraulic fluid source and that two separate sources may be used.

Since each of the air piston sets 711, 713 include the use of separate hydraulic pistons 714, 715 through separate hydraulic fluid inlets 732, 733. Movement of each of the air piston sets 711, 713 may occur simultaneously, as shown in FIG. 8 or may be offset, as shown in FIG. 9. In other words, hydraulic fluid can be fed to hydraulic piston 714 to initiate movement of the air piston set 711 at a different time from the hydraulic fluid that is fed to hydraulic piston 715. The ability to offset the two air piston sets 711, 713 allows for an offsetting of the strokes on either side of the air pump 710. The fluid flowing into the hydraulic pistons 714, 715 may be controlled through the use of solenoid valves within the hydraulic fluid lines.

The use of the split rod design allows for the offsetting of peak air pressures from both ends of the air pump simultaneously. In other words peak air pressure at one end of one of the air piston sets occurs at a different time to the peak air pressure exiting the end of the opposite air piston set. An example of the offset configuration is shown in FIG. 9. This allows for constant output flow from the air pump and no dead zone. When used with a hydraulic oil source, such as in a vehicle braking system, the ability to use an air pump with no dead zone provides for constant opposition which provides a smooth power cycle.

Turning to FIGS. 10A-B, the playback mode for the double stage split rod configuration will be briefly described. It will be understood that the figures show a schematic representation of one embodiment of the air pump with air lines connecting the piston bores and air storage tank. It will be understood that the air pump, described herein, is not limited to the configuration of air lines shown herein. The air pump includes two stems 722, 723 including three pistons connected to each stem. Each piston is located within a respective air piston bore that, as discussed above, is divided into parts A and B by the location of the piston within the bore. Piston bores 726B, 728A, 730B, 746A, 748B and 750A are shown in FIG. 10A, and piston bores 726A, 728B, 730A, 746B, 748A and 750B are shown in FIG. 10B.

FIG. 10A illustrates a first stroke in the playback mode, with both stems, moving to the right, in the direction of arrows R. Air is supplied by air storage tank 100 to air ports 810, 811 through the air lines that fluidly connect the air storage tank to the respective air ports 810, 811 which feed the air into air piston bores 730A (shown clearly in FIG. 10B) and 750B (shown clearly in Figure B). Movement of the stems 722, 723, and the air pistons connected thereto, in the direction of arrow “R”, then moves air between adjacent piston bores. As discussed above, solenoid valves that are closed are represented by the symbol

, and solenoid valves that are open are represented by the symbol

.

Air flows between the air piston bores, entering through receiving ports, represented generally by numeral 820 and out of air piston bores through delivery ports, represented generally by numeral 830. The direction of the air flow, between adjacent air piston bores, is shown by the arrows in FIG. 10A.

On the return stroke, shown in FIG. 10B, the stems 722, 723, and the air pistons connected thereto, move in the direction of arrow “L”. Air is fed from air storage tank 100, threw the air lines and into the air piston bores through receiving ports 820 and delivery ports 830. It will be understood that receiving ports are air ports that receive air flowing into the air piston bore and delivery ports are air ports that allow air to flow out of the air piston bore(s) or the air storage tank. The direction of the air flow, between adjacent air piston bores, is shown by the arrows in FIG. 10B.

It will also be understood that in the split rod configuration, due to the separate hydraulic fluid feeds, it is possible to use only one side of the air pump, i.e. one of the rods with attached pistons, if required.

While the air pump, or sets of air pistons, in the above have been described in terms of including a series of three air pistons, it will be understood that the air pump disclosed herein is not limited to this configuration. For example the air pump may include a series of four or five or more air pistons. The air pump may also include only two air pistons. Other combinations of pistons within the air pump may be used while following the overall operation of the air pump disclosed herein.

In one embodiment, the air pump may include a central stem, or stems, having a series of pistons on one side that are greater in size than a series of pistons on the other side. Each series of pistons having pistons of decreasing diameter. In this configuration, the air is passed from the larger piston series across the pump to the smaller piston series. The overall flow of the air is therefore through a series of pistons that decrease in size, however, rather than being all in one row on one side of the air pump they are separated.

In operation, the air pump may be driven by hydraulic means or any suitable mechanical means that is operable to initiate movement of the pistons. While the air pump examples provided include the use of hydraulic means, it will be understood that alternative embodiments may be used that are operable to drive the stem and associated air pistons, such as a mechanical link connected to the hydraulic piston through a fluid link, oil coupling medium or through a direct mechanical connection.

Each of the air piston bores may include a pressure relief valve that monitors the pressure within the bore, or portion of the bore within which it is located. Such valves may be used to ensure that the pressure does not exceed the operational pressures allowed. Likewise, similar pressure relief valves may be used in the hydraulic piston bore(s).

It will be understood that while not specifically identified in the attached figures, each of the air lines may include one or more one-way valves or check valves to control the flow of air within each air line. In addition, where there is a requirement to control the input and/or output of air, solenoid valves may be used. One or more heat sinks may also be used to lower the air temperature for easier storage of the air in the air storage tank.

The air pump may include one or more cooling devices positioned to reduce the temperature of the air flowing through the air pump, and specifically between piston bores. Reducing the temperature of the air will allow for greater storage capacity in the air tank and will also reduce the impact on the hardware and extend the life of the components and reduce the maintenance required.

The air pump described herein may be used in any system that requires or uses a driving force, such as that supplied by the air pump in playback mode. The air pump may also be used in any system that requires rapid compression and storage of air.

As an example, when the air pump includes a hydraulic piston that is driven by an injection of hydraulic fluid, the injection of the fluid initiates movement of the stem within the air pump which drives the air pistons and compresses and stores air. In the playback mode, as described above, the air from the storage tank is used to drive the air pistons which in turn drive the hydraulic piston which ejects the hydraulic fluid from the hydraulic piston bore. The ejected hydraulic fluid can then be used to drive a device, system, that requires an input of hydraulic fluid, such as a hydraulic pump or a separate device. Alternatively, the air may be used to directly drive a device, such as an air motor.

As an example of a use of the air pump, the air pump may be connected to a vehicle braking system and the hydraulic fluid that drives the hydraulic piston is fed to the air pump during the braking action of the vehicle. In one embodiment, the air pump may be placed between the hydraulic source and the air tank to provide a source of braking and a pre-set restrictor valve may be used in the air line before the air tank. Hydraulic fluid moves the hydraulic piston, which in turn moves the air pistons, and the air that is pumped out of the air pump to the storage tank may be fed to the storage tank via a pre-set restrictor valve, i.e. a speed bump. The air flow opposition is transmitted back through the air pump to the hydraulic source, in this case the drive wheels and axle, thereby providing an additional source of braking.

While this invention has been described with reference to illustrative embodiments and examples, the description is not intended to be construed in a limiting sense. Thus, various modification of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments. Further, all of the claims are hereby incorporated by reference into the description of the preferred embodiments.

Any publications, patents and patent applications referred to herein are incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety. 

1. An air pump configured to allow for movement of air to and from an air storage tank comprising: a housing having at least one stem passing therethrough, the stem configured to reciprocate along its longitudinal axis within the housing; at least two air pistons located within respective air piston bores within the housing, each of the air pistons connected to the at least one stem and configured to reciprocate, along the longitudinal axis of the at least one stem, within its respective air piston bore, each air piston bore comprising a first air line fluidly connecting the air piston bore to the air storage tank and at least one second air line fluidly connecting the air piston bore to an adjacent air piston bore.
 2. The air pump according to claim 1, further comprising an actuator for moving the at least one stem along its longitudinal axis within the housing.
 3. The air pump according to claim 1, wherein the first air line is configured to allow passage of air from the air piston bore to the air storage tank when the air leaving the air piston bore is of equal or greater pressure than the air in the air storage tank.
 4. The air pump according to claim 1, comprising three pistons located within three adjacent piston bores.
 5. The air pump according to claim 1, wherein the actuator is a hydraulic piston.
 6. The air pump according to claim 1, wherein the air pump comprises two separate sets of at least two air pistons, each set connected to and located on opposing ends of a stem.
 7. The air pump according to claim 1, wherein the air pump includes three air pistons, the second air piston having a smaller diameter relative to the first and the third air piston having a smaller diameter relative to the second.
 8. The air pump according to claim 1, comprising a pair of stems, each operable to move within the housing, each stem including two or more air pistons connected thereto and a hydraulic piston located at one end thereof.
 9. The air pump according to claim 8, wherein the pair of stems are configured to move within the housing in opposing direction to each other.
 10. The air pump according to claim 8, wherein the pair of stems are configured to move within the housing in an offset arrangement.
 11. The air pump according to claim 1, wherein each air piston bore comprises at least one air line fluidly connected to ambient air.
 12. The air pump according to claim 2, wherein the actuator is a mechanical link.
 13. The air pump according to claim 1, wherein each air piston bore comprises two or more air lines fluidly connecting adjacent air piston bores.
 14. The air pump according to claim 1, wherein each of the air lines includes at least one control valve.
 15. An air pump configured to allow for movement of air to and from an air storage tank comprising: a housing having a first and second stem passing therethrough, each of the stems configured to reciprocate along their longitudinal axis within the housing; a first air piston connected to the first stem and received within a first air piston bore located within the housing, the first air piston being operable to reciprocate within the first air piston bore along the longitudinal axis of the first stem; a second air piston connected to the first stem and received within a second air piston bore located within the housing, the second air piston being operable to reciprocate within the second air piston bore along the longitudinal axis of the first stem; a first air line, fluidly connecting the first piston bore to the air storage tank; a second air line, fluidly connecting the first piston bore to the second piston bore; and a third air line fluidly connecting the second piston bore to the air storage tank; a third air piston connected to the second stem and received within a third air piston bore located within the housing, the third air piston being operable to reciprocate within the third air piston bore along the longitudinal axis of the second stem; a fourth air piston connected to the second stem and received within a second air piston bore located within the housing, the fourth air piston being operable to reciprocate within the second air piston bore along the longitudinal axis of the second stem; a fourth air line, fluidly connecting the third piston bore to the air storage tank; a fifth air line, fluidly connecting the third piston bore to the fourth piston bore; and a sixth air line fluidly connecting the fourth piston bore to the air storage tank
 16. The air pump according to claim 15, further comprising at least one actuator, for moving at least one of the first and second stem along its respective longitudinal axis within the housing.
 17. The air pump according to claim 15, further comprising a first and a second actuator, the first actuator for moving the first stem along its respective longitudinal axis within the housing and the second actuator for moving the second stem along its respective longitudinal axis within the housing.
 18. A method for moving and compressing air using an air pump comprising a series of air pistons fluidly connected to each other and to an air storage tank, the method comprising: (a) moving air between adjacent air pistons within the air pump; and (b) allowing air to flow from each air piston to the air storage tank when the air pressure of the air leaving the air piston is equal to or exceeds the pressure in the air storage tank. 